When it was first discovered, Ceres was believed to be a ‘missing planet’ – but it’s now considered a dwarf planet alongside Pluto.

‘Right now, all we can say is that the material reflects 40 percent or more of the light falling on it,’ said NASA principal investigator Chris Russell of UCLA.

‘This limit is because of the resolution of the camera at this distance from Ceres. If the final answer … is that it reflects all the light that falls on it, then the most probable reflector would be ice.’

Dawns previous images have shown features which scientists admit are ‘puzzling’ – such as craters and mysterious ‘bright spots’.

‘We expected to be surprised, we did not expect to be this puzzled,’ Russell said last week.

When the Dawn probe sent back the first clear images of Ceres surface – hinting that there could be geysers and craters on the mysterious, dark rock, the wilder reaches of YouTube took the ball and ran with it.

‘Alien contact! Time to prepare!’ says one YouTuber.

Dawn will be gently captured into orbit around Ceres on March 6.

As the spacecraft delivers better images and other data, the science team will be investigating the nature and composition of the dwarf planet.